Essentially, it's a race. When a new car is announced and priced,
the first person to physically find Musk and hand him a check
will get the first one.

For example, the first Model S went to a Tesla board
member, Steve Jurvetson, because he carried a blank check around
in his wallet. When he spotted info about the Model S in a packet
of board meeting notes, he plucked out his check and "slid it
across the table to Musk."

There's an even more extreme example.

Entrepreneur
Konstantin Othmer told Vance that when he spotted a
story in Wired that mentioned how Tesla planned to release a
second version of its super-car, the
Roadster, he immediately emailed Musk, who responded that he
would sell Othmer the car, but that he would have to pay $200,000
up front. Tesla released the first Roadster in early 2010,
charging $109,000 for the sleek, ultra-fast automobile.

Musk made Othmer come to Tesla HQ on a Sunday with the money and
to sign papers agreeing that he knew that Tesla didn't know when
the car would be ready, or even what its exact specifications
would be. Othmer didn't care.

"My guess is that it will be the fastest car on the road. It'll
be four-wheel drive. It's going to be insane," he told Vance.
"And I don't really think that will be the real price. I just
don't think Elon wanted me to buy it."